In the field of scuba diving it is well known that it is sometimes difficult for a diver to find his or her way back to the dive boat. There are several situations which make this especially difficult. Specifically, when the diver cannot see the dive boat, navigating a route to the boat is difficult. Further, when several dive boats are within a close range, it can be difficult to find the boat from which the diver embarked.
Other devices have been produced for underwater communication, or for determining range and bearing of objects under water. Typical of the art are those devices disclosed in the following U.S. Patents:
______________________________________ U.S. Pat. No. Inventor(s) Issue Date ______________________________________ 4,563,758 C.J. Paternostro Jan 7, 1986 4,604,733 B.F. Brown, et al. Aug 5, 1986 5,185,605 J.W. Roberts, Jr., et al. Feb 9, 1993 5,331,602 C.B. McLaren Jul 19, 1994 ______________________________________
That device disclosed by Paternostro ('758) is provided for acoustic communication between divers. This type of device, however, does not assist a diver in finding his or her way back to a dive boat. Specifically, the '758 device is not capable of determining a distance or a direction to a dive boat.
The device taught by Brown, et al., ('733), is an apparatus for determining range and bearing between a transponder and a transponder interrogator. Brown, et al., incorporate two spaced-apart hydrophones on the transponder for use in determining the direction toward the interrogator. The bearing is determined by the transponder and is communicated to the interrogator by sending a delayed signal, the delay being indicative of the bearing. Because of the configuration of this apparatus, the orientation of the two transducers must be maintained in order to give useful bearing information. For example, if the transponder is rotated ninety degrees (90.degree.), the diver will receive an indication that he or she has moved in the opposite direction that amount, and not that the transponder has moved.
McLaren ('602) teaches an acoustic navigation and diving information system and method using the global positioning system (GPS). Specifically, the system utilizes a base buoy and a remote buoy. A diver carries a tracking unit which is in continuous communication with the buoys, which are monitored by a base station unit. This type of system determines positioning data using triangulation methods.
Finally, Roberts, Jr., et al., ('605), teach a device for monitoring the water temperature in a diver's environment, and further for monitoring the air pressure within the diver's air tank. The '605 device is not capable of determining direction or distance from a diver to a dive boat, but is used to alert a diver when he or she is swimming in dangerous conditions of which he or she may not otherwise be aware.
Although these devices provide means for communicating with and between divers, or for monitoring the activity of divers, with the exception of the Brown, et al., device, these devices do not provide for the monitoring of the position of a dive boat by the diver. Because of the complexity of the Brown, et al., device, the integrity of the device is easily compromised. Specifically, the Brown, et al., device does not provide for the direct computation of the direction and distance to the dive boat at the interrogator unit.
Therefore, it is an object of this invention to provide a means for determining the distance and direction from a diver to a dive boat.
Another object of the present invention is to provide such a means whereby the diver uses an acoustic transponder to determine the distance and direction to the dive boat.
Still another object of the present invention is to provide a means whereby the transponder incorporates a plurality of transducers for determining the direction to the boat.